Determining tensile yield stresses from small punch tests: a numerical-based scheme

The Small Punch (SP) test serves the rapid screening of mechanical material properties and the assessment of material degradation in a virtually non-invasive way. It requires robust frameworks for the derivation of mechanical properties and microstructure{mechanical property correlation. In particular, one of them is the tensile yield stress y, which is commonly associated with an elastic-plastic transition force with h denoting the SP disc thickness and a dimensionless coefficient considered to be constant. In the present paper we show that cannot be taken as a constant. Instead a new self-consistent data reduction scheme is proposed for the determination of the yield stress which is based on the curvature of the force-displacement curve rather than a single force level. The scheme derives from finite element simulations of a wide range of strength coefficients and hardening exponents of power-law flow. The method is validated by comparing the yield stress predictions with the actually implemented yield stresses in the simulations, using power law and other types of flow rules, as well as experimental data from different steels. It is shown that the uncertainty of yield stress determination by SP tests can be largely reduced as compared to the traditional scheme.

HAEHNER Peter;  SOYARSLAN Celal;  GULCIMEN Betul;  BARGMANN Swantje; 

2019-08-01

ELSEVIER BV

JRC116416

0264-1275 (online),   

www.elsevier.com/locate/matdes,    https://publications.jrc.ec.europa.eu/repository/handle/JRC116416,   

10.1016/j.matdes.2019.107974 (online),